The present invention relates to a method for the formation of flat articles into groups.
The invention finds application to advantage in the food industry where there is a requirement for flat articles such as chocolates, toffees, cookies and the like to be arranged in groups; indeed reference is made in the following specification to this same art field, albeit implying no limitation in general scope.
The prior art embraces methods for the formation of flat articles into groups; in a first method, disclosed in UK Patent application No 2 203 412, the articles advance randomly along a horizontal conveying surface to a station where they are taken up singly onto the periphery of a vacuum wheel and directed toward a transfer station. Before entering the transfer station, the articles pass in front of a sensor serving to pilot the operation of a device by which each article in turn is detached from the wheel and added to a group, positioned on edge inside a magazine which is caused simultaneously to recede through a distance substantially identical to the thickness of the single article. During this formation step, the group is inclined relative to a horizontal plane and guided laterally by a fixed wall which the articles engage in sliding contact. Thereafter, having accumulated a selected number of articles, the magazine is rotated in such a manner as to release the already formed group of articles into a container, which is then directed toward further operating stations.
The formation of flat articles into groups by this method betrays certain drawbacks.
Firstly, the sliding contact between the articles and the fixed side wall can jeopardize the correct formation of a group of articles, for example, in the event that the articles should bind or stick as the result of sliding friction.
This is a drawback that significantly limits the operating speed of packaging equipment as described above.
Secondly, the receding movement of the magazine has the effect of jerking the articles, positioned in contact one with another, with the result that the articles themselves can suffer damage; this again dictates the need for the operating speed of the equipment to remain below a desirable higher value.
The operating speed is limited additionally by the brevity of the interval allowed in which to bring about the step of detaching the articles from the vacuum wheel, which is enabled by a sensor located immediately preceding the transfer station.
The prior art embraces another method, disclosed in U.S. Pat. No. 5,595,280, whereby the flat articles are advanced in an ordered succession toward a vacuum wheel furnished with pockets, each accommodating a single article. The articles are then taken up by a linear conveyor and caused to advance, positioned on edge, along a first feed direction and toward a transfer station where they are formed into groups and removed subsequently from the conveyor by an extractor device of which the action is produced by movement in a direction perpendicular to the first feed direction aforementioned.
This further method of forming articles into groups presents the drawback that the articles are made to pause at the transfer station, so that the groups can be distanced along the second feed direction and the risk of contact with successive articles advancing on the conveyor thus eliminated. The need to include a pause consequently occasions a certain reduction in the operating speed of the equipment.
The object of the present invention is to provide a method whereby flat articles standing on edge can be formed into groups without any of the drawbacks mentioned above.
The stated object is duly realized in a method according to the present invention for forming flat articles into groups, which comprises the steps of advancing a first succession of articles along a first path toward a transfer station, at a set tempo and in such a way that each article is caused to assume a predetermined position in space when occupying the transfer station, and advancing the articles through the agency of pocket type first conveyor means along a second path extending from the transfer station to a release station in a feed direction substantially normal to the position in space assumed by the articles, thereby creating a second succession of articles disposed on edge. The method disclosed also comprises the step of forming a succession of distinct groups along the pocket type first conveyor means, each consisting in a plurality of articles spaced apart at a given constant pitch, of which the last article in each group is distanced from the first article of the next group in succession by a gap of length greater than the pitch length, obtainable by selectively and controllably varying the linear velocity of the pockets of the first conveyor means with the passage of each group.
The present invention also relates to a device for the implementation of such a method.
In accordance with the invention, flat articles are formed into groups by a device comprising means by which to advance a first succession of articles along a first predetermined path toward a transfer station, at a set tempo and in such a manner that each article is caused to assume a predetermined position in space when occupying the transfer station, and first conveyor means affording pockets by which the articles are advanced along a second predetermined path extending from the transfer station to a release station in a feed direction substantially perpendicular to the position in space assumed by the articles, thereby creating a second succession of articles disposed on edge, wherein the linear velocity of the pockets afforded by the first conveyor means, and therefore the rate of feed at which the articles advance along the second path, can be selectively controlled in such a way as to allow the formation of a succession of distinct groups along the first conveyor means, each consisting in a plurality of articles spaced apart at a predetermined constant pitch, of which the last article in each group is distanced from the first article of the next group in succession by a gap of predetermined length greater than the pitch length.